The invention relates to a device for detecting the filling level, particularly of a liquid in a container, by an electro-mechanical transducer secured to a diaphragm, by which transducer the diaphragm is made to oscillate with an oscillatory displacement. The transducer operates with electrical circuit means for establishing oscillations within the diaphragm, as well as within a holder of the diaphragm on which the diaphragm is fastened by means of a cylindrical intermediate member. Characteristics of sonic signals imparted to the liquid by the transducer are dependent on the amount of liquid present in the container. These characteristics are employed by the electrical circuit means to measure the liquid level.
Such known devices may not have very high resistance against various external influences which act on them. These influences may impair the operation of the device. Such influences result, for example, in distortions of the diaphragm, which may be brought about by temperature fluctuations or by deformation of the fastening of the cylindrical intermediate member with the holder. Furthermore, acoustic impairments and deformation of the diaphragm can occur, which can impair the measurement.